Slur cam for knitting machines



Aug; 7, 1945. F. s. WISBECKER 2,381,376

SLUR CAM FOR KNITTING MACHINES Filed Jan. 19, 1945 Patented Aug. 7, 1945 UNITED STATES PATENT OFFICE SLUR CAM FOR KNITTING MACHINES Frank G. Weisbecker, Glenside, Pa.

\pplication January 19, 1945, Serial No. 573,586

6 Claims.

The present invention relates to improvements for use on straight bar knitting machines, and more particularly to improvementsin slur cocks or cams for such machines.

Heretofore, slur cams have generally been made in one piece with the working face of the cam arranged to advance the sinker-actuating jacks, and thereby to engage the yarn and kink the same. With such an arrangement, when the sinkers are advanced by the jacks to force the yarn between the needles as the yarn is fed from a yarn carrier, the

needles particularly in a reinforcing operation, are flexed backwardly by the tension placed on the yarn, in the loop forming operation. Unless the needles are permitted to return from this flexed position before the slur cam leaves the jacks, the spring action of the flexed needles is likely to force the sinkers back too far, with the result that the yarn will be displaced from the sinker catch; and then when the needle descends to complete the loop, the yarn, due to its displacement, not infrequently, is either split or broken. The obvious result is the frequent production of defective merchandise.

Accordingly,- to overcome this disadvantage the slur cam of the present invention is provided with novel means, relatively movable with respect to the working face of the cam, which allows for return of the needles from their flexed position before the slur cam moves out of contact with the jacks.

Also, e. g. in the making of stockings on the well known straight bar knitting machine, during yarn sinking, the up and down movement of the needles is not adjustable to provide for short or long kinks in the yarn and the corresponding difference in length of the loops. Therefor as the body portion of the stocking is made of relatively short loops for tighter knitting than the reinforced parts of a stocking at the heel and toe, the needles, during yarn sinking for the loose coarse knitting (in making the longer loops for the reinforced parts of the stocking) must stand closer to the sinkers. The movement of the needlebar for either tight or loose knitting is accomplished by apparatus well known in the art, and accordingly is not explained here in detail, since the present invention relates only to detailed improvements in slur cams, per se.

If the working face of the known slur cams were elongated to prevent any sudden backward movement of the sinkers, by the return of the flexed needles to normal unflexed position, there advance the sinkers to would result pinching of the yarn and breaking of the stitches during the inward movement of the needles in forming the longer yarn loops of the reinforcing course. Accordingly, an object of the present invention is to provide a novel slur cam for straight bar knitting machines, wherein the working face of the nose of the cam is supplemented by an .extensible sliding portion, which trails the cam, and presents a working face which is slightly set back from the normal straight portion of the working face of the slur cam. This constructionserves to not only prevent the sudden release of the sinkers, as above described,'but also compensates for the inward movement of the needle bar and the closer stand of the needles to their adjacent sinkers when making the reinforcement part of the stocking or other garment. By thus presenting a surface which is set back from the straight working face of the nose of the cam, pinching of the yarn loops between the needles and sinkers is prevented for each reinforcing course of the yarn.

Other objects and advantages of the present invention will be apparent to those skilled in the art from the following description when considered in connection with the accompanying drawing, which illustrates a preferred embodiment of the device.

In the drawin 1 Figure 1 is a top plan view of the relevant parts of a straight bar knitting machine, showing my novel slur cam moving in the direction of the arrow.

Fig. 2 is a cross-section view taken along the line 2-2 of Fig. 1 showing the parts of aconventional straight bar knitting machine with my novel slur cam mounted on the slurcock or slur cam box.

Referring to the details of the present invention as illustrated in the drawing, there are included only those parts of a conventional straight bar knitting machine that cooperate with the specific construction of the present invention. Such parts include the usual row of sinkers m, the usual corresponding row of dividers II, the sinker operating jacks I2, the verge plate l3, and the needle bar l4 with its usual row of needles IS. on the opposite side of the jacks I2 is mounted the usual slur cock or cam box IS. A bracket I1 extends from the cam box and secured thereto by bolts l8 and I9 is a slur cam 20. The latter engages the jacks l2 and forces them forward to advance the sinkers III, with the yarn 9, into their yarn sinking positions, as is well known in the art.

It is the particular novel construction of the slur cam 20, as shown in the drawing, that is the subject of the present invention. It com-.

prises a nose portion having inclined, divergent working faces 2| and 23 at the ends with an intermediate straight working face 22. See Fig. 1. These cam faces operate the Jacks l2 and advance the sinkers ill to their respective yarn sinking positions in the conventional manner. The straight working face of the nose of the cam is slightly beveled, inwardly, as is customary.

The nose of the cam 20 is grooved along its working faces, and retained within this groove there is slidably mounted a bar 25. The latter, in general, is of the same shape as the nose of the cam 20, including a straight face 21 and rearwardly divergent end faces 26 and 28. The straight face, however, of the bar 25 is somewhat longer than the corresponding face of the cam. To retain the bar in the groove of the cam, the bar is slotted, longitudinally as at 29 and a pin 30, extending across the groove in the cam and through the slot in the bar, functions to guide and limit the endwise movement of the bar 25, relative to the cam 20. As illustrated in the drawing, the straight working face of the bar is set back slightly from and parallels the corresponding face of the cam 20. Guided by the pin 30, and the walls of the groove in the cam, the bar 25, will move to a trailing position; as in Fig. 1, due in part to its inertia, and also upon contact with the first of the jacks l2 which is encountered as the slur cam is moved in one or the other direction of its normal reciprocating motion. With the bar 25 thus extended from the trailing face of the cam, as shown in Fig. 1, the jacks I2 and their respective sinkers ill, in line withthe bar 25 cannot release, but owing to the fact that the bar 25 is set back slightly from the straight working face 22, the jacks and sinkers may recede sufficiently to permit the needles l5 to straighten up from a flexed position due to yarn tension, or to allow for the inward movement of the needle bar l4 and needles l5 when the yarn is being fed by a reinforcement yarn carrier.

Thus, this invention provides a novel form of slur cam for straight bar knitting machines, adapted to control the'positions of the sinkers in the making of the reinforcement part of s stocking or other garment. Specifically, it is effective to compensate for the longer yarn loops and the closer stand of the needles to the sinkers during this part of the machine's operation, and also to provide a limited release and backward movement of the jacks and sinkers, after the main body of the cam has cleared the jacks.

While the features of my invention have been illustrated and described in considerable detail as an embodiment of only one form thereof, other changes and modifications which will now appear to those skilled in the art, may be made without departing from the scope of the present invention. Reference should be had to the appended claims to determine the scope of the present invention.

I claim:

1. In a straight bar knitting machine embodying sinkers and cooperating needles: 9, slur cam having a nose portion for imparting forward motion to said sinkers into yarn sinking position between said needles; and means slidably mounted on said cam and adapted to extend rearwardly thereof in a trailing position, in either direction of movement of the cam, and presenting a straight working face slightly set back from and parallel to the outermost working face of the nose of the cam to permit limited return of the sinkers with inward movement of the cooperating needles during yarn-sinking of a reinforcing course.

2. The combination as defined in claim 1 in whi h the means siidably mounted on the cam comprises: a bar having a slot extending longitudinally thereof; and a part projecting from the cam into said slot to define the limits of lengthwise movement of the bar, relative to the cam.

3. A slur cam for imparting motion to the sinkers of a straight bar knitting machine comprising: a nose portion having a substantially straight working face and rearwardly-extending, divergent surfaces at the ends thereof; a bar slidably mounted on the nose portion of the cam, the said bar having generally the shape of the nose. the straight working face thereof being of greater length than the corresponding face of the nose; and means on the cam engaging the said bar to retain it with its straight working face parallel to the corresponding face of the cam and set back slightly therefrom, said last named means also serving to' limit the sliding movement of the bar relative to the cam.

4. The combination of claim 3 in which the last named means comprises, a pin and slot connection between the cam and the sliding bar.

5. The combination of claim 3 in which the bar element, at the limit of its movement relative to the nose of the cam, presents a straight working face which is parallel to and somewhat longer than the straight portion of the cam nose.

6. A slur cam for imparting motion to the sinkers of a straight bar knitting machine comprising: a nose portion having a substantially straight working face and rearwardly-extending divergent surfaces at the ends thereof, said nose portion having an elongated groove along its straight working face and opening through the said divergent surfaces at its ends; a flat bar slidably retained in said groove and having a substantially straight working face of somewhat greater length than the straight working face of said nose portion, said bar at its ends having divergent surfaces of the same general contour as the divergent surfaces of the said nose portion and extending rearwardly to a substantially straight surface which is parallel to its said straight working face, said bar being provided with a slot extending lengthwise thereof; and a pin mounted in the nose portion of the cam and extending vertically through the slot in the said bar to retain the bar in sliding engagement within the groove, the pin and the walls of the groove cooperating to guide and limit the movement of the bar relative to the cam, and to retain the bar in its operative position rearwardly of the cam with its straight working face parallel to and slightly set back from the line of the straight working face of the nose of the cam.

FRANK G. WEISBECKER. 

